Lefteris wrote:
It is only natural if you overload the system with some other process, such as copying 40G with dd, other processes will become slower. It has nothing to do with MonetDB, your favorite web browser will also take 3 minutes to open (USB interface eats up CPU, and dd eats up the IO channel). Especially if you run a DBMS on a machine, which is already resource consuming, the system will slow done alot even with small unrelated processes. Thats is why a dedicate server is usually better.
I still find it a bit hard to believe that with the complete fair I/O scheduler of recent kernels, disk IO can slow a a query down from 0.5s to > 6 minutes.
I don't think you will be able to find anything about the IO scheduler of Fedora. Actually this is part of the Linux Kernel and not configurable. The only suggestion that I can make (which I don't know if it works for IO), if you *must* copy 40gigs while you are shredding documents, is to run the copy command with "nice", that is: bash$ nice copy /path/a path/b
lefteris
ionice works approximately the same for IO. This seems to solve the problem. -- John